Between the roles of the fovea and macula, which is most importnat?

One contains other. The fovea is the central point of the macula and contains the photoreceptors for you most acute central vision. They are both important, but the central fovea could be consider most important.
Both. The fovea is part of the macula. Arguably the fovea is most important for central vision used for reading but the macula also plays a major role in central vision.